Dr. Strieby, of American Telephone and Telegraph Co., demonstrates Bell Labs' recent invention of a solar battery, capable of producing sufficient electric voltage from any light source to operate a telephone. However, most telephone services have large power plants and storage batteries, which function when no light is available, so there is no reason to substitute a solar battery. Dr. Strieby next demonstrates a "personalized telephone" prototype ("like Dick Tracey's"), which functions like a mini-FM broadcasting station using transistors activated by a solar battery. This is only experimental and short-range because of the length of antenna required to transmit beyond a few hundred feet. Dr. Strieby then explains how a solar battery is built, using silicon from DuPont that is purified through a diagrammed process. Ultimately, with the addition of arsenic and boron gas, the thin sheets of silicon create a positive/negative juncture that allows light to become electricity.